a) two solids- sugar and salt. It is a heterogenous mixture as constituents can be identified separately.
b) a solid in liquid- sugar in water. It is a homogenous mixture as the components are uniformly spread throughout the solution.
Solid in a liquid can also be a hetrogenous solution for eg. sand and water.
c)liquid in liquid-oil in water. It is a heterogenous mixture.
d)liquid and gas- carbonated beverages. They are homogenous mixture.